关于select的问题

Question

http://expert.csdn.net/Expert/TopicView1.asp?id=3028745

Answer 1

<script language = "JavaScript"> 
sall=new Array();
sall[0]=new Array("泉州","1","1");
sall[1]=new Array("厦门","1","2");
sall[2]=new Array("福州","1","3");
sall[3]=new Array("石狮","1","4");
sall[4]=new Array("武汉","2","5");
sall[5]=new Array("沙市","2","6");
sall[6]=new Array("孝感","2","7");
sall[7]=new Array("信阳","3","8");
sall[8]=new Array("郑州","3","9");
sall[9]=new Array("南阳","3","10");
function changeselect(selvalue)  
   { 
      document.myform.Nclassid.length=0;  
      var selvalue=selvalue;
      var i;
      for(i=0;i<sall.length;i++) 
{
    if(sall[i][1]==selvalue) 
       {
   var newOption1=new Option(sall[i][0],sall[i][2]);
document.all.Nclassid.add(newOption1);
}
}
}
</script> 
<form method="post" name="myform" action="ru_query.asp"> 
<select name="classid" onChange="changeselect(document.myform.classid.options[document.myform.classid.selectedIndex].value)" size="1"> 
<option selected value="">未指定条件</option> 
<option value='1'>福建省</option>
<option value='2'>湖北省</option>
<option value='3'>河南省</option>
</select> 
<select name="Nclassid"> 
<option selected value="">未指定</option> 
</select>